Xbox one x turns on for 3-5sec then off

I recently followed TronicsFix YouTube video on how to clean your Xbox one x and how to take it apart. It was fairly easy- I took everything apart except for the fan and heat sink being that once I got to them they weren’t all that dirty and I was able to use a compressed air can to blow any minor dust out. I followed the video backwards to put it back together and that went well…or at least I thought? Now when I try to turn it on it comes on for 3-5sec and then immediately powers off. It’s not connected to the controller anymore either. Nothing comes up on the tv screen. I’m assuming I did something wrong when putting back together. It was 100% fine when I took it apart. Any thoughts?